1. Field of the Invention
The present invention relates to an embroidery data processing apparatus which processes embroidery data needed to control a sewing machine to form an embroidery pattern on one or more work sheets, and in particular to such an apparatus for processing embroidery data which command a sewing machine to form a shadowed embroidery pattern including an original embroidery pattern and one or more shadow embroidery patterns.
2. Related Art Statement
There is known an embroidering manner, shown in FIG. 14, in which a "shadowed" embroidery pattern is produced by forming, using a sewing thread with a light color, embroidery stitches of an original embroidery pattern, a, such as an alphabet character, and forming, using another sewing thread with a darker color, embroidery stitches of one or more "shadow" embroidery patterns, b, which are contiguous with the original pattern a. The produced shadowed embroidery pattern a, b exhibits a good three-dimensional effect to observers.
A first conventional method, shown in FIG. 15, in which a shadowed embroidery pattern is produced is to embroider a selected pattern, subsequently change the position of an embroidery frame, or a work sheet held by the frame, relative to a sewing needle, and embroider the same pattern once more.
A second conventional method is to produce, as embroidery data to be supplied to a sewing machine, shadowed-pattern embroidery data including original-pattern embroidery data corresponding to an original embroidery pattern and shadow-pattern embroidery data corresponding to one or more shadow embroidery patterns. The second method may be carried out by an embroidery data processing apparatus which is essentially provided by a microcomputer and is equipped with an image scanner, a display, a mouse, etc. When an operator or user inputs, in the processing apparatus, sets of coordinate values defining the outline of a shadow embroidery pattern, the processing apparatus divides, based on the input data, the inside area of the shadow embroidery pattern bounded by the outline thereof, into quadrangular and/or triangular blocks, according to a known outline-defining-data processing algorithm, and produces, as shadow-pattern embroidery data, sets of block-defining data defining respective quadrangular and/or triangular outlines of the blocks. Otherwise, an operator may directly input, as shadow-pattern embroidery data, sets of coordinate values defining stitch positions, in the processing apparatus.
However, the first method in which the same pattern is embroidered twice suffers from the problems that the quality of embroidery is low because the two patterns overlap each other in a large area and that two-fold amounts of time and thread are needed. In addition, a produced shadowed embroidery pattern lacks stitches to fill areas, c, shown in FIG. 15. Moreover, the stitches of the shadow embroidery pattern do not extend all in the same direction and accordingly the shadowed embroidery pattern cannot enjoy a three-dimensional effect.
The second method requires the operator to input, in the processing apparatus, sets of coordinate values defining the outline of each shadow pattern, by using the mouse, etc., so that the processing apparatus may produce shadow-pattern embroidery data based on the input data, or to directly input, as shadow-pattern embroidery data, sets of coordinate values defining stitch positions where a sewing needle of a sewing machine penetrates a work sheet. However, it is cumbersome for the operator to input sets of coordinate values in the processing apparatus, and it takes a long time to obtain shadowed-pattern embroidery data.